Material Mechanics 材料力学

1. Material Mechanics 材料力学
This course mainly learned about the Mechanical Properties of Material (Important mechanical properties are strength. stiffness hardness. and ductility..) and tensile . cut . torsion . bending . stress. Strain . and Hooke ’s law .the most important in the course is the Stress-Strain Diagram .
Intensity: 强度
Strength of materials, ability to withstand an applied stress without failure
Compressive strength , capacity to withstand axially directed pushing forces
Tensile strength , maximum stress while being stretched or pulled before necking
Shear strength , the ability to withstand shearing
Stiffness:
Stiffness is the resistance of an elastic body to deformation by an applied force along a given degree of freedom (DOF) when a set of loading points and boundary conditions are prescribed on the elastic body.
hardness, modulus . Young Modulus(E)= stress/ strain
Stress ：is the internal resistance offered by a unit area of the material from which a member is made to an externally applied load.
Normal Stress : The intensity of force , or force per unit area , acting normal to △A is defined as the normal stress , σ.Since △Fz is normal force to the area then σz =lim A Fz ∆∆ △A is the very small area ,and △Fz is the very small force .
Strain: also called unit deformation, is found by dividing the total deformation by the original length of the bar.
Normal Strain : The elongation or contraction of a line segment per unit of length is referred to as normal strain . such as line AB, this line lies along the n axis and has an original length of △l, after deformation , points A and B are displace to A ’ and B ’and the line becomes a curve having a length of △l ’, the change in length of the line is therefore △l ’-△l , As point B is chosen closer and closer to point
A , the length of the line becomes shorter and shorter ,such that △l →0 . Also ,this cause
B ’to approach A ‘ such that △l ’ →0 .Consequently , in the limit the normal
strain at point A and in the direction of n is ε=lim
l
l l ∆∆-∆' . Yield strength is the lowest stress that produces a permanent deformation in a material.
Compressive strength is a limit state of compressive stress that leads to failure in the manner of ductile failure or brittle failure Tensile strength or ultimate tensile strength is a limit state of tensile stress that leads to tensile failure in the manner of ductile failure or brittle failure. Tensile strength can be quoted as either true stress or engineering stress.
Fatigue strength is a measure of the strength of a material or a component under cyclic loading,[6] and is usually more difficult to assess than the static strength measures.
A typical stress-strain diagram for a low-carbon steel is shown in the figure. It can be seen that during the first phase of loading, the plot of stress versus strain is a straight line, indicating that stress is directly proportional to strain. After point A on the diagram, the curve is no longer a straight line. This point is called the proportional limit. As the load on the sample is continually increased, a point called the elastic limit is reached, marked
B in the figure. At stresses below this point, the material will return to its original size and shape if the load is removed. At higher stresses, the material is permanently deformed. The yield point is the stress at which a noticeable elongation of the sample occurs with no apparent increase in load. The yield point is at
C in the figure. Applying still higher loads after the yield point has been reached causes the curve to rise again. After reaching a peak, the curve drops somewhat until finally the sample breaks, terminating the plot. The highest apparent stress taken form the stress-strain diagram is called the ultimate strength.
（胡克定律）Hooke’s low :The degree to which a structure deforms or strains depends on the magnitude of an imposed stress ,.For most metals that are stressed in tension and at relatively low levels .stress and strain are proportional to each other through the relationship : σ=E*εHere E represent the constant of proportionality , which is called the modulus of elasticity or Young’s modulus . 举例：布氏硬度：用一定大小的载荷P，将直径D的合金球压入试样表面，一定时间后卸除载荷，试样表面留下压痕，测量d，计算表面压痕S。

HB=P/S
=P/πDh
=2P/πD（D- D2-d2 ）
布氏硬度测量铸铁等金属材料，而陶瓷及矿物材料的测量用莫氏硬度。

Forexample: Brinell hardness
Putthe alloy ball of diameter D to press into the sample surface through a certainsize of load P, after a certain time, remove the load, there is indentation in the sample surface, measure and calculate the surface indentation S.
Brinellhardness measures cast iron and other metal materials, ceramic and mineralmaterials with Moh’ s hardness measurement
2.Heat Transfer Theory 传热学基础：热量传递分为三种：热传导，热对流和热辐射 Basis of heat transfer: heat transfer is divided into three types: heat conduction, thermal convection and thermal radiation
热传导：是指在不涉及物质转移的情况下，热量从物体中温度较高的部位传递给相邻的温度较低的部位，或从高温物体传递给相接触的低温物体的过程，简称导热。

Heat conduction: is a process which in the case does not involve substance transfers , the heat from the parts of object with higher temperature delivery to the adjacent parts with lower temperature, or from hot objects pass to the contacted cold objects.
在一定的温度梯度，一定时间，经过一定面积所传递的热量可用傅立叶公式计算：
the heat passing through a certain area in a certain temperature gradient and a certain time, can be obtained by Fourier formula :
Q=—λ（L T T 1
2 ）At
式中：Q —传导热量 ；T 2-T 1—材料内两点的温度差 ；L —材料内两点的距离 A —传热面积 ；λ—材料的导热系数 ；t —传热时间 ；
Where : Q —is the heat of conduction ; T 2-T 1—is Temperature difference between objects ; L —is Distance between two points ; A —is Heat transfer area ; λ—is The thermal conductivity coefficient of the material ; t —is the Heat transfer time
For example: 一端插在火炉中的金属棍的另一端会有灼热感 when we insert metal rod into the furnace , we will fell hot in another side of it .
热对流：是指不同温度的流体各部分由相对运动引起的热量交换。

对流换热量的基本计算公式是牛顿冷却公式。

Thermal convection: refers to the heat exchange caused by the relative movement of fluid with different temperature.
对流传热量可用下面公式计算：the heat of thermal convection can be obtained through this formula : Qc=αc (T-T f )At
式中：Qc —对流传热量 ；T —放热流体的温度 ；Tf —受热流体的温度 ；
A — 传热面积 ；t —传热时间 ；αc —对流传热系数 ；
Where : Qc —is the heat of thermal convection ; T —is temperature of Exothermic fluid ; Tf —is the temperature of heated fluid ; A —is the heat transfer area ; t —is the heat transfer time ; αc —is the Convective heat transfer coefficient
Example: the Heating tablets (暖气片) is a good example .
热辐射：是物体受热后，内部原子振动而出现的一种电磁波能量传递现象。

它是波长在0.1～100微米之间的电磁辐射，因此与其他传热方式不同，热量可以在没有中间介质的真空中直接传递。

Thermal radiation: is a phenomenon that an electromagnetic wave energy transfer caused by the vibration of internal atomic after the object was heated . .例子：Example: there is a good example : The sun deliver enormous energy to the earth is by radiation. 太阳就是以辐射方式向地球传递巨大能量的。

在单位时间内物体单位面积所辐射发出的能量Q由stefan-boltzmann 求得:
The energy radiated by the object in per unit area and per unit time can be Calculated by this formula :Q=CT4 式中：Q—辐射能量；T—热力学温度；C—辐射系数。

.where : Q—is the energy by radiate ; T—is the Thermodynamic temperature; C—is the Radiation coefficient .
机械设计基础：Machine Design
在这门课里学了平面机构，凸轮机构，齿轮传动，蜗杠蜗轮机构，带传动和链传动，轴和轴承等。

In this course, I mainly learned planar mechanism, cam mechanism, gear drive, belt drive, shaft and bearing and so on.
平面机构：所有构件都在同一平面或相互平行的平面内运动的机构。

Planar mechanism: refers to the institutions which movements of all components are in the same plane or the parallel plane.
例如：如图为曲柄摇杠机构，曲柄滑块机构等
For example: as shown in the figure: this is crank-shake stick mechanism, slider-crank mechanism
平面机构运动副及其分类：planar mechanism kinematic pair and its classifications:
运动副:使构件与构件之间直接接触并能产生一定相对运动的连接称为运动副。

如轴与轴承，活塞与汽缸，齿轮与齿轮形成的连接。

Kinematic pair: refers to the connection which makes the direct contact between components and can produce a certain relative movement.
运动副分为低副和高副。

低副又分为移动副和转动副。

It can be divided into lower pairs and higher pairs. Lower pairs divided into moving pair and rotating pair.
低副是两构件通过面接触组成的运动副。

Lower pair: refers to the kinematic pair composed of two components through surface contact.
移动副是组成运动副的两个构件只能沿某一轴线作相对移动的运动副。

如内燃机与活塞。

Moving pair: refers to the kinematic pair in which the two components can only move relatively along a axis. Such as: the movement of internal combustion engine and piston.
转动副是组成运动副的两个构件只能在某一平面内作相对转动的运动副。

如轴与轴承。

Rotating pair: refers to the kinematic pair in which the two components can
only rotate in a planar. Such as: the movement of shaft and bearing.
高副是两构件间通过点或线接触组成的运动副。

如车轮与钢轨。

Higher pair: refers to the kinematic pair composed by the two components through point or line contact. Such as: the movement of wheel and rail. 平面机构自由度的计算：the calculation of freedom of planar mechanism 自由度是指构件相对于参考系的独立运动。

Freedom: refers to the independence movement of the component relative to reference system.
计算公式formula ：F=3n-2P L -P H 式中F 表示机构的自由度，n 表示机构中的活动构件数，P L 表示机构中低副数目，P H 表示机构中高副数目。

在平面机构中一个活动构件有3个自由度，每个低副引入两
个约束，使构件失去两个自由度，每个高副引入一个约束，使构件失去一个自由度。

Where: F represents the freedom of mechanism, n represents the numbers of activities components in mechanism, P L represents the numbers of lower pair in mechanism, P H represents the numbers of higher pair in mechanism. An activities component has three freedoms in mechanism, each lower pair with two constraints, so that the component lose two freedoms, each higher pair with one constraints, so that the component lose one freedom.
凸轮机构由凸轮，从动件和机架组成。

Cam mechanism composed of cam, follower and rack.
凸轮是一种具有曲线轮廓或凹槽的构件，通常作连续等速转动。

The cam is the component which with curve contours or grooves, usually do continuous constant velocity rotation.
凸轮机构的分类 classifications of cam mechanism ：按形状分：according to the shape:
1） 盘形凸轮：它是一个绕固定轴转动并且具有变化向径的盘状构件。

Disk cam: it is the discoid component which around a fixed axis rotation and has changes direction.
2)移动凸轮：当盘形凸轮的转轴位于无穷远时，凸轮相对机架作直线运动，这种凸轮称为移动凸轮。

例如：如图为移动凸轮机构
Moving cam: it is the cam which does straight line movement relative to the rack when the shaft of disk cam is located in infinity. For example: this is the moving cam mechanism:
3)圆柱凸轮：将移动凸轮卷成圆柱体即成为圆柱凸轮。

Cylindrical cam: makes the moving cam volumes into cylinder to become the cylindrical cam.
齿轮传动：gear drive
类型按工作条件不同可分为闭式传动和开式传动。

According to the working conditions it can be divided into: closed drive and open drive. 传动比drive ratio :i=z z w w 1
221
w1, w2 分别为齿轮的转速，Z1，Z2分别为齿轮的齿数。

W1, w2 represents the rotation speed of gear; Z1, Z2 represents the teeth number of gear.
齿轮的加工方法：切削法，铸造法，轧制法和冲压法等。

其中最常用的是切削法。

切削法按其原理不同可分为仿形法和展成法。

The processing method of gear: cutting method, casting method, rolling method and stamping method etc. The most commonly used is the cutting method. Cutting method can be divided into profiling method and generating method according to the different principles.
仿形法是在普通铣床上利用渐开线齿形的成形铣刀将被加工齿轮齿槽部分材料铣掉来来切制齿形的齿轮加工方法。

其有点是加工方法简单，不需要专用机床。

缺点是精度难以保证，生产效率低。

Profiling method: it is the gear tooth processing method which uses the milling cutter of involute tooth mill out partial materials of the gear alveolar to be machined to form gear tooth in the ordinary milling machine. Its advantages are the processing method is simple and does not need a dedicated machine. The disadvantages: the accuracy is difficult to guarantee and production efficiency is low.
展成法是利用一对齿轮无侧隙啮合使两轮的齿廓互为包络线的原理加工齿形的齿轮加工方法。

采用的刀具主要有齿轮插刀，齿条插刀和滚刀。

Generating method: it is the gear tooth processing method which uses a pair of gear backlash meshing to make the tooth profiles of two gear to be envelope with each other to processing gear tooth. The cutter used are mainly gear insert cutter, rack insert cutter and hob.
齿轮失效形式：1.轮齿折断，2。

齿面磨损，3.齿面点蚀，4.齿面胶合
The types of gear failure: 1.broken gear tooth, 2. tooth surface wear, 3. tooth surface pitting, 4. tooth surface gluing.
齿轮传动的润滑：其主要作用是减少摩擦，磨损，导出和散发摩擦热，对传动件起防腐作用，因而可提高传动的效率和经济性，提高齿轮传动的承载能力和使用寿命。

Lubrication of gear drive: its main role is to reduce friction, wear, export and distribute friction thermal, antiseptic effect thus can improve the transmission efficiency and economy, increase the carrying capacity and service life of the gear drive.
润滑方式选择：齿轮传动的润滑方式主要取决于齿轮的圆周速度大小。

在开式及半开式齿轮传动中，因为速度较低，采用润滑油或润滑脂进行定期润滑。

在闭式齿轮传动中，当齿轮的圆周速度v≦12m/s时，通常采用浸油润滑，当齿轮的圆周速度v>12m/s时，由于圆周速度大，齿轮搅油剧烈，且粘附在齿面上的油易被甩掉，不宜采用浸油润滑，而应采用喷油润滑。

The choice of lubrication types: the lubrication of gear drive depends on the circumference speed. In open and semi-open gear drives, because of the lower speed, we can use lubricating oil or grease to lubricate regularly. In enclosed gear drives, when the circumference speed of the gear V below 12m/s, commonly using immersion oil lubrication, when the circumference speed V above 12m/s, since the speed is high, gear churning intense and the adhesion oil easily get rid of the tooth surface , thus should not use immersion oil lubrication, but fuel injection lubrication.
齿轮传动的优点：1.能保证恒定的传动比，2.适用的功率和圆周速度范围广，3.结构紧凑，4.效率高，5.工作可靠且寿命长。

Advantages: 1. can guarantee a constant transmission ratio, 2. the applicable power and peripheral speed is wildly, 3. compact structure, 4. high efficiency, 5. work reliable and
long life.
缺点：1.制造齿轮需要专用设备和刀具，成本较高，2.对制造和安装精度要求高，3.不宜用于长距离的传动。

Disadvantages: 1. the manufacture of gears require special equipment and cutters, so that the cost is high. 2. require high accuracy of manufacture and installation.
带传动：如图主要由主动轮1，从动轮2和张紧在两轮上的环形传动带3组成。

环形传动带可分为：平带，V带，多楔带和同步齿形带。

Belt drive: it is mainly composed by driving wheel 1, driven wheel 2 and the ring drive belt 3 tension on the two-ring. The ring belt can be divided into: flat belt, V belts, ribbed belts and timing belt.
优点：1.带具有良好的弹性，可以缓和冲击，吸收振动，传动平稳，噪声小；2.过载时，带在带轮上打滑，可防止零件损坏，起安全保护作用；4.结构简单，制造安装和维护方便，成本低。

Advantages: 1. Belt has good elasticity, could mitigate the impact, absorb vibration, smooth transmission, low noise, 2. the belts can slipping in the pulley when overload to prevent damaging the components, 3. the structure is simple, manufacturing, installation and maintenance is easy, low cost.
缺点：1.带在带轮上有相当滑动，不能保证着准确的传动比；2.传动效率低，带的寿命较短；3.传动的外廓尺寸大；4.带传动需要张紧，支承带轮的轴和轴承受力较大；5.带传动中的摩擦会产生火花，不宜用于易燃易爆的场合。

Disadvantages: 1. since the belt can slide in the pulley, so that can not guarantee accurate ratio, 2. transmission efficiency is low with shorter life, 3. belt drive need to tension, so that the shaft and bearing supporting the pulley force is great, 4. Transmission of large outside dimensions, 5. belt drive friction create sparks, not suitable for the occasion of the flammable and explosive.
轴是用来支承旋转运动的零件，并传递转矩和运动。

按承受载荷不同分为转轴，传动轴和心轴。

Shaft is the parts used to support the rotary motion and transmit torque and motion. According to the load bearing, it can be divided into rotary axis, drive shaft and mandrel.
转轴:工作中既承受转矩又承受弯矩的轴，如齿轮减速器的轴。

Rotary axis: it is the shaft that both to withstand torque but also bending moment when working. Such as: the shaft of gear reducer.
传动轴：只承受转矩而不承受弯矩的轴，如汽车中的传动轴。

Drive shaft: It is the shaft that only to withstand torque and not withstand bending moment. Such as: the drive shafts in automotive.
心轴：只承受弯矩而不承受转矩的轴。

Mandrel: it is the shaft that only to withstand bending moment and not withstand torque.
轴常用的材料是碳素钢（45钢应用最广），合金钢（40Cr）及球墨铸铁。

The materials commonly used for shaft are: carbon steel (45 steel is the most widely used), alloy steel (such as: 40Cr) and ductile iron.
轴主要由轴颈，轴头和轴身3部份组成。

The Shaft mainly composed by shaft neck, shaft head and shaft body.
倒角：轴端和各阶梯端面均有大小倒角，其作用是：1.导入相配零件，2.防止划伤相配零件和操作者，3.尖角易被磕碰而变形，以致妨碍相配零件的安装。

Chamfer: in the ends of shaft and ladder face are all have chamfers. Its roles are: 1. import the matched parts, 2. to prevent scratches the matched parts and operator, 3. the sharp corners are easily bumped to deformation so as to obstruct the installation of the matching parts.
圆角：为了减少应力集中，轴上各段直径变化处，均有大小不同的圆角。

Fillet (rounded corner): in order to reduce stress concentration, there are different sizes of fillets at the diameter changes position of shaft.
轴承：用于确定旋转轴与其他零件相对运动位置，起支承或导向作用的零部件。

它的主要功能是支撑机械旋转体，用以降低设备在传动过程中的机械载荷摩擦系数。

电机没有轴承的后果就是根本不能工作。

Bearing: it is the parts used to determine the relative movement position of rotary axis and other parts, and as the role of supporting and guiding. Its main function is to support the mechanical rotating body to reduce the load coefficient of friction of the mechanical equipment in the drive process. Such as: the consequence of motor without bearing is that it can not work at all.
按轴承工作的摩擦性质不同可分为滑动摩擦轴承和滚动摩擦轴承两大类。

滚动轴承就是将运转的轴与轴座之间的滑动摩擦变为滚动摩擦，从而减少摩擦损失的一种精密的机械元件。

滚动轴承使用维护方便，工作可靠，起动性能好，在中等速度下承载能力较高。

与滑动轴承比较，滚动轴承的径向尺寸较大，减振能力较差，高速时寿命低，声响较大。

According to friction properties when bearing working, it can be divided into: sliding friction bearing and rolling friction bearing.
Rolling friction bearing is a precision mechanical component that can transform the sliding friction between shaft and shaft seat into rolling friction so that reducing the friction loss.
Advantages of rolling bearing：1. us e and maintenance is easy, 2. reliable work and good start performance, 3. at medium speed, the carrying capacity is higher.
Disadvantages: compared with sliding bearing, the radial size of rolling bearing is larger, the damping capacity is poor, lower life when high speed and noisier. 润滑：滑动轴承可以采用润滑脂，也可以利用传动构件的润滑油进行润滑。

Lubrication: plain bearings can use grease, and you can also use lubricating oil of the drive components for lubrication.
润滑的作用：1.减少摩擦及磨损，2.延长疲劳寿命,3.排出摩擦热、冷却，4.也有防止异物侵入轴承内部，或防止生锈、腐蚀之效果。

The role of lubrication: 1.to reduce friction and wear, 2.extend the fatigue life, 3. discharge of friction heat, cooling, 4. to prevent foreign matter intrusive into bearing, or to prevent rust and corrosion.
失效：1.接触疲倦失效，2. 磨损失效Failure: 1.contact fatigue failure, 2.wear failure.
机械设计基础课程设计 Fundamentals of Machine Design Course Design
运用机械设计课程和其他有关的课程去解决生产实际中的机械设计问题举例：带式运输机的传动装置设计，要求运输带有效拉力1600N ，带速0.45m/s ，滚筒直径250mm, 滚筒长度400mm 。

分为三个部分：
In this course, use of mechanical design course and other related courses to solve the problem of mechanical design in actual production. My course design topic is belt conveyor gearing design. Requirements: the conveyor belt tension is 1600N (), the speed of belt is 0.45m/s, the diameter of roller is 250mm and the length of roller is 400mm. The steps of my design can be divided into three parts:
1. 设计计算：确定传动方案，确定总传动比，计算电动机的功率，转速，选择电动机等 First, Design calculations: include: determine the drive schemes and total drive ratio, calculate the motor power and speed to choose the type of motor. And so on.
所需电动机功率用下式计算：Pr=
ηp w , 式中Pw 为工作机所需有效功率(KW)，η为电动机到工作机的总效率。

Pw=1000
Fv ，式中F 为工作机的圆周力（N ），如运输机上运输带的有效拉力；v 为工作机的线速度（m/s ）。

The power of required motor can be calculated by this formula ：Pr=ηp w , where: Pw represents the effective power of required motor (unit symbol: KW), η represents the total efficiency of the motor to a working machine. Pw=1000
Fv , where: F represents the circumferential force of the working machine (unit symbol: N, Newton ), such as the effective tension of belt in the conveyor, v represents the line speed of the working machine (m/s). 总传动比i=n n w 0
,式中n 0为电动机的满载转速(r/min)，n w 为工作机轴的转速(r/min)。

The total drive ratio i=n n w 0
, where: n 0 represents the full load speed of motor (r/min), n w
represents the ration speed of the working machine shaft (r/min).
2. 绘装配草图：选取一定比例，选择轴承型号及校核轴承寿命等.Second, paint assembly sketch: select a certain percentage, select the type of bearing and check on bearing life. 传动轴的最小轴径d ≥A 3n
p , 式中P 为传递的功率（KW ），n 为轴的转速（r/min ）,A 为材料影响系数。

The minimum shaft diameter of drive shaft can be calculated by this formula: d ≥A 3n
p , where: p represents the power transferred (KW), n represents the ration speed of shaft （r/min ）, A is the impact factor of material.
3.写说明书： Three, write design specification.
机械设计基础实验：
在这门课程，我们对一些机械零件进行了分析和测试。

例如我们进行了齿轮加工的模拟。

齿轮加工方法有两种基本加工类型。

成形法和展成法
常用的齿轮加工方法有：铣齿.滚齿. 插齿
In this experiment we mainly to get to know some mechanical parts and analyze them .
For instance ,Gear machining method has two basic types. Forming method and generating method
Commonly used in gear cutting methods are: milling.Hobbing.Gear Gear are most commonly produced via hobbing, but they are also shaped, broached, cast, and in the case of plastic gears, injection molded. For metal gears the teeth are usually heat treated to make them hard and more wear resistant while leaving the core soft and tough.
材料科学基础：
This course is the most important subjects in material science but which is also nearly the most difficult course in our study. And it mainly talking about several parts which including the Fundamentals of crystallography, defects of the crystal, fick`s low, and one component system/binary equilibrium phase. The course told us about the fundamental of the material.
Which means it is the basic knowledge of our professional course.
三种晶包结构：
The three unit cell structure typical of metals : body-centered cubic such as ferrite, face-centered cubic such as austenite and hexagonal close-packed.
相图
Phase diagrams are graphical representations of what phases are present in an alloy system at various temperatures, pressures and compositions. Phase diagrams are constructed using the information gathered from cooling curves. Cooling curves are time temperature plots generated for various alloy compositions and provide information about phase transition temperatures. These diagrams tell us which phases are present at different compositions and temperatures for slow cooling or heating conditions that approach equilibrium. During the rapid solidification of many alloys, compositional gradients are created and cored structures are produced.
材料科学基础实验Experiment of Material Science and Engineering：
材料的性能由材料内部结构决定，金相显微分析是金属材料科学研究中重要的研究方法，可以观察组织细节和缺陷。

Material properties determined by the internal structure of materials, microstructure analysis is an important metal material science research methods, organizational details and defects can be observed.
原理：由二维金相式样磨面或者是薄膜的测量和计算来确定合金的三维空间形貌，从而建立合金成分，组织和性能间的定量关系。

Principle: the two-dimensional metallographic samples or film measurements and calculations to determine the three-dimensional morphology of the alloy in order to establish alloy components, tissue and the quantitative relationship between performance.
金相显微镜的原理和使用：利用光线的反射原理，第一次放大的透镜称物镜objective，第二次放大称目镜eyepiece。

两种光路系统：直立式和倒立式
金相式样的制备：取样--粗磨（用砂轮等整为规则形状的式样）--细磨（用金相砂纸由粗到细，用力均匀，磨痕grinding crack方向要一致然后换方向与之前要垂直vertical）--抛光（放在抛光机上抛光，加入适当的抛光液如氧化铝粉的悬浮液）--浸蚀（如果直接抛光在显微镜下只能看到光亮的磨面，例如两相合金，具有较高负电位的浸蚀被溶解，具有较高正电位的不被浸蚀，产生两相高度差）--观察
The principle and the use of metallurgical microscope: the use of light reflection principle, the first zoom lens, said lens, said second zoom eyepiece. Two kinds of optical system: upright and inverted
Metallographic Preparation of style: Sampling - coarse grinding (such as grinding wheel to regular shape) - finely ground (with metallographic sandpaper from coarse to fine, even force, to be consistent with the direction of the wear scar and then change direction before vertical) - polishing (polished on polishing machines, add the appropriate slurry such as alumina powder suspension) - erosion (polishing directly under the microscope if you can only see the light of the grinding surface, such as two-phase alloys, has a high negative potential of erosion is dissolved, with high positive potential of being etched, resulting in two-phase height difference) - Watch
举例：共析碳钢，铁素体由于有较高的负电位被溶解，渗碳体有较高正电位被保护。

For example: eutectoid carbon steel, ferritic high negative potential due to be dissolved, cementite has a higher positive potential is protected.
快速成型技术Rapid Prototyping Technology
什么是快速成型技术？Rapid prototyping technology is a new digital forming technology which based on the principle of discrete - accumulation forming. It is Under the control of computer, according to the CAD model, through the accurate accumulation of materials, manufacture prototypes or parts. It is an advanced manufacturing technology .
Characteristics：
l) can made arbitrarily complex three-dimensional geometric entities.(可以制造任意复杂的三维实体)
2) rapid （快速性）
3) a high degree of flexibility.（高度柔性）
4) No cutting, noise and vibration, and environmental protection.（无切割，噪音，振动，环保）
5)adopt non-contact processing, no tools to replace and no wear .（采用非接触式加工，不用更换工具，无磨损）
applications :
(1) the design verification and functional verification in new product development process, （新产品开发过程中的设计验证与功能验证。

）
(2)If the complexity parts is difficult to determine, you can use the RP technology for pilot production in order to determine the best rational process.（对于难以确定的复杂零件，可以用RP，技术进行试生产以确定最佳的合理的工艺。

）(3) the direct production of single pieces, small batch and special complex parts.（单件、小批量和特殊复杂零件的直接生产。

）
.(4) rapid tooling. （快速制造模具）
In this course , I learned several advanced rapid prototyping technology , such as : stereolithography apparatus (光固化快速成形), laminated object manufacturing (叠层实体制造)，selected laser sintering (选择性激光烧结)
For example : selected laser sintering (选择性激光烧结)
SLS：Is by the use of laser to selectively layered sintered the solid powder, and to get the parts of desired shape by making the solidified layer which is formed by sintering to layers curing .
工艺过程：The entire process, including the establishment of CAD model and data processing→, powder, →sintering and→post-processing.
可用于SLS的材料：Materials for SLS：
Materials for SLS are paraffin wax, polymer, metal, ceramic powder and their composite powder materials
材料成型技术Material Molding Technology 机械制造基础Machine Build In this course , I learned the four aspects of knowledge : Metal liquid forming, metal plastic forming , metal welding molding and mechanical processing. (the heat treatment of forming pieces ).
Liquid forming , in other word , casting ,is a method to get a certain shape, size parts rough by melting the metal alloy and then it solidified forming .(液态成形即铸造，是通过使金属合金熔化和凝固成形，获得一定形状，尺寸零件毛坯的方法。

)
熔炼金属常用的设备有冲天炉、电弧炉、感应炉、电阻炉、反射炉等.
The equipment commonly used in Melting metal are: cupola, electric arc furnace, induction furnace, resistance furnace, reverberatory furnace. Casting methods include :Sand casting process(砂型铸造), investment casting （熔模铸造）, metal casting（金属铸造）, high pressure die casting（压力铸造）, centrifugal casting（离心铸造）。

砂型铸造工艺流程图：Sand casting process flow diagram
The basic raw material for making sand is casting sand and sand binder.(制造砂型的基本原材料是铸造砂和砂型粘结剂。

)
The most commonly used casting sand is siliceous sand（最常用的铸造砂是硅质砂。

）The most widely used molding sand binders is clay, and a variety of drying oil or semi-dry oil, water-soluble silicate or phosphate and synthetic resin can be used as a sand binder.（应用最广的型砂粘结剂是粘土，也可采用各种干性油或半干性油、水溶性硅酸盐或磷酸盐和各种合成树脂作型砂粘结剂。

）The role of sand binder is to bond the loose sand together to form the molding sand ，So that the sand mold and the core has a certain strength。

（砂型粘结剂的作用是将松散的砂粒粘结起来成为型砂，使制成的砂型和型芯具有一定的强度。

）
举例：如汽车发动机的缸体和缸盖，船舶螺旋桨以及精致的艺术品，都是通过铸造技术制造的。

Such as the cylinder block and cylinder head of car engine, ship propeller and exquisite artworks , are manufactured all by casting technology.
.锻压forging and stamping : is a forming method which through the hammer , anvil block , punch of forging machinery or the die to pressure on the billet , and then generate plastic deformation , in order to obtain the required shape and size parts .( 锻压是锻造和冲压的合称，是利用锻压机械的锤头、砧块、冲头或通过模具对坯料施加压力，使之产生塑性变形，从而获得所需形状和尺寸的制件的成形加工方法。

)
Forging and stamping Classified by the manner of shaping : forging and stamping
Forging Classified by the deformation temperature :
hot forging热锻(Forging temperature is higher than the recrystallization temperature of the billet metal锻造温度高于坯料金属的再结晶温度)
cold forging冷锻(Forging temperature is lawer than the recrystallization temperature of the billet metal 锻造温度低于坯料金属的再结晶温度)
warm forging温锻（At room temperature 室温）
for example :The beginning recrystallization temperature of steel is approximately 727 ° C, but generally 800 ℃as the demarcation line, higher than 800 ℃is hot forging; between 300 ~ 800 ℃.is called warm forging or semi-hot forging (钢的开始再结晶温度约为727℃，但普遍采用800℃作为划分线，高于800℃的是热锻；在300～800℃之间称为温锻或半热锻。

) Based on the moves of billet, forging can be divided into :free forging, upsetting, extrusion, forging, closed die forging, closed upsetting.(根据坯料的移动方式，锻造可分为自由锻、镦粗、挤压、模锻、闭式模锻、闭式镦锻。

)
The equipments of forging : forging hammer(锻锤air hammer空气锤and steam - air hammer蒸汽-空气锤.) and hydraulic machine（液压机）.。